Added source files.

src/HelloWorld.asm

@@ -0,0 +1,17 @@
+.section .data
+    hello:
+        .ascii "Hello, World.\n"
+
+.section .text
+    .global _start
+
+_start:
+    mov $1, %rax
+    mov $1, %rdi
+    mov $hello, %rsi
+    mov $14, %rdx
+    syscall
+
+    mov $60, %rax
+    xor %rdi, %rdi
+    syscall